Who: Frances Arnold, Caltech
Definition: Cellulolytic enzymes break down the cellulose found in biomass so it can be used as a feedstock for biofuels.
Impact: Increased use of cellulosic biofuels could cut greenhouse-gas emissions and reduce reliance on oil.
Context: Processes for making cellulosic biofuels are still too expensive to be practical. A number of companies are racing to find a solution.

TR10: Cellulolytic Enzymes

Frances Arnold is designing better enzymes for making biofuels from cellulose.

In December, President Bush signed the Energy Independence and Security Act of 2007, which calls for U.S. production of renewable fuels to reach 36 billion gallons a year--nearly five times current levels--by 2022. Of that total, cellulosic biofuels derived from sources such as agricultural waste, wood chips, and prairie grasses are supposed to account for 16 billion gallons. If the mandates are met, gasoline consumption should decline significantly, reducing both greenhouse-gas emissions and imports of foreign oil.

The ambitious plan faces a significant hurdle, however: no one has yet demonstrated a cost-competitive industrial process for making cellulosic biofuels. Today, nearly all the ethanol produced in the United States is made from the starch in corn kernels, which is easily broken down into the sugars that are fermented to make fuel. Making ethanol from cheaper sources will require an efficient way to free sugar molecules packed together to form crystalline chains of cellulose, the key structural component of plants. That's "the most expensive limiting step right now for the large-scale commercialization of [cellulosic] biofuels," says protein engineer Frances Arnold, a professor of chemical engineering and biochemistry at Caltech.

The key to more efficiently and cheaply breaking down cellulose, Arnold and many others believe, is better enzymes. And Arnold, who has spent the last two decades designing enzymes for use in everything from drugs to stain removers, is confident that she's well on her way to finding them.

Cellulosic biofuels have many advantages over both gasoline and corn ethanol. Burning cellulosic ethanol rather than gasoline, for instance, could cut cars' greenhouse-gas emissions by 87 percent; corn ethanol achieves reductions of just 18 to 28 percent. And cellulose is the most abundant organic material on earth.

But whereas converting cornstarch into sugar requires a single enzyme, breaking down cellulose involves a complex array of enzymes, called cellulases, that work together. In the past, cellulases found in fungi have been recruited to do the job, but they have proved too slow and unstable. Efforts to improve their performance by combining them in new ways or tweaking their constituent amino acids have been only moderately successful. Researchers have reduced the cost of industrial cellulolytic enzymes to 20 to 50 cents per gallon of ethanol produced. But the cost will have to fall to three or four cents per gallon for cellulosic ethanol to compete with corn ethanol.

Ultimately, Arnold wants to do more than just make cheaper, more efficient enzymes for breaking down cellulose. She wants to design cellulases that can be produced by the same microörganisms that ferment sugars into biofuel. Long a goal of researchers, "superbugs" that can both metabolize cellulose and create fuel could greatly lower the cost of producing cellulosic biofuels. "If you consolidate these two steps, then you get synergies that lower the cost of the overall process," Arnold says.

Consolidating those steps will require cellulases that work in the robust organisms used in industrial fermentation processes--such as yeast and bacteria. The cellulases will need to be stable and highly active, and they'll have to tolerate high sugar levels and function in the presence of contaminants. Moreover, researchers will have to be able to produce the organisms in sufficient quantities. This might seem like a tall order, but over the years, Arnold has developed a number of new tools for making novel proteins. She pioneered a technique, called directed evolution, that involves creating many variations of genes that code for specific proteins. The mutated genes are inserted into microörganisms that churn out the new proteins, which are then screened for particular characteristics.

Are the superbugs, as described in the article, only found in fungi? What about termite bellies, carpenter ant bellies, woodland critters living in the decomposing masses of leaves and twigs, or grasses found in nature? I would suspect that a superbug capable of digesting or consuming woody materials will be found in woods - while a different critter that digests grassy materials will live in prairie environments. I would even bet that a good field biologist could find some simliar bugs living in waterways or bog like areas where leave, twigs and grasses would be delivered via a stream of water.

Nature has been feeding itself for ions, are we trying to reinvent the wheel or just increase the effciency?

2720 Days Ago

02/20/2008

I have wondered why they don't just combine some termites with all the cellulose and let them do their business. Then process the resultant mess, and save some to start the next batch. I wonder if this has been tried. I understand that their is a Southern type of termite that is much more active than the Northern type.

I do fear that we might genetically produce some organism that will destroy live plants in the environment on a large scale. I am pretty sure we have no oversight on this possibility. Do a search on grey goo. Grey goo is the scenario where nanotechnology destroys all living things.

Read it before. As I indicated, perhaps a superbug that is specific to a particular food source has better enzymes in it's gut to digest the local foods. The south american termites may be best for digesting jungle-chow, while another variety (maybe african plains) may be better suited to chomping on grassy materials. Get these two together, legally married and have some offspring that may not care where the food source comes from because they can feed on any variety of biomass.

my 2 cents

mko

2265 Days Ago

05/20/2009

As far as termites go if we utilize http://food-science-jobs.com/

2720 Days Ago

02/20/2008

cellulolytic enzymes

the article states that when fully exploited

cellulose ethanol will significantly reduce the

usage of gasoline.

From what I have read 'significant' is less than

3.5% of our gasoline usage. I don't see this as

significant.

The only thing significant is the terrific increase in food prices that has resulted from

using corn to make ethanol. Typical gov't

action.

2720 Days Ago

02/20/2008

Butanol can be mixed with gasoline in high percentages. It is about equal to gasoline in energy, and can be shipped in pipelines.It can also be used to produce electricity. Cellulosic ethanol production does not use grain. Anyway corn is mainly used to feed animals, as in "corn fed beef." Let the cattle eat grass. They will be a lot happier than stuck in a stall. Plus we eat too much meat for our health anyway. Also, obesity is the worlds largest health problem, not malnutrition.

2720 Days Ago

02/20/2008

Good work on the part of the professor. But long term sustainability of both microbial and enzymatic bioreactants culturing and nurturing,absolutely essential for fermentation

potential to eventually replace industrail scale fuel energy in today's world. very good but to keenly follow the progress.

2719 Days Ago

02/21/2008

The math is simple, but the media always resorts to terms like "significant." In 2022, the U.S. is expected to consume the equivalent of 170 billion gallons of gasoline. 36 billion gallons of ethanol is the equivalent of 23 billion gallons of gasoline, making that amount 13.5% of automobile fuel. NOTE: We currently use about 145 billion gallons, so the ethanol will not even account for the expected increase by 2022, meaning we will use more gasoline in 2022 than we do today. Is this "significant"? Gasoline accounts for about 43% of our oil consumption, meaning that in 2022, that amount of ethanol would amount to the equivalent of about 6% of our oil. Is that significant in light of the fact that we will use 15% more oil in 2022 than we do today? It takes energy to make ethanol. Most of that 36 billion gallons will be corn ethanol, which basically breaks even on energy. This cuts into those percentages, I would say "significantly."

2715 Days Ago

02/25/2008

The media may be wrong in the way it calculates ethanol percentages.But the impact of biofuels on food price will actually influence the way people spend.Food price rise is not a bad thing as many people seem to suggest.Infact food prices have remained low for too long a time ,which has resulted in poverty becoming a permanent feature for those involved in agriculture in developing countries.The macro effect of biofuels as i see it is competition of acreage between crops , high food price which forces people to opt for more fuel efficent vehicles.This shift is already visible with fall in the no of SUVs sold and niche vehicles like hybrids becoming mainstream.The net effect is a fall in gasoline consumption as people will have to make more provision for basic needs like food.

2701 Days Ago

03/10/2008

Now I'm not doubting your claim that ethanol is a break even fuel but DOE claims that: "Each gallon of corn ethanol today delivers as much as 67% more energy than is used to produce it."

http://www1.eere.energy.gov/biomass/ethanol_myths_facts.html

So I can only wonder where DOE gets it's input from?

2701 Days Ago

03/10/2008

You are totally contradicting yourself. Cellulosic ethanol will replace food based ethanol. Why not help promote a positive solution, rather than curse the darkness.

2715 Days Ago

02/25/2008

Dangerous

Is there any way this can throw the earth's biological balance off. if you alter these enzymes can they mutate and destroy our food source.

The Definition of an expert is a person that avoids all the little mistakes on the way to the big fallacy.

Pete Seeger

2701 Days Ago

03/10/2008

Who knows. Nobody is looking at this, as far as I know. The EPA seems to be brain dead.

2702 Days Ago

03/09/2008

bio-fuels

If obesity is more of a problem than malnutrition, then let's improve the technology for liposuction and convert the fat into bio-fuel, thus solving two problems at once.

2692 Days Ago

03/19/2008

THIS WILL MAKE AN EXCELLENT BUMPER STICKER!

2695 Days Ago

03/16/2008

this is the way to go..........

2692 Days Ago

03/19/2008

Food Prices

Mexico has been hit particularly hard due to rising corn prices. This will not increase the standard of living for third world countries. In fact, third word countries will remain poor for a longer period of time because they won't be able to make the transition to an industrial based economy. This transition is the only real way of bringing people out of poverty because more people can move out of agriculture and into manufacturing jobs.

2597 Days Ago

06/22/2008

Not So Top 10

I find this whole top 10 list disappointing. There must be thousands of science news items every day equally exciting. One could randomly pick 10 of them to make a list of equal quality to TR's top 10. I think that a more accurate title for this list would be "10 Of The Top Million Exciting Ideas Being Worked On"

In order for an item to be "likely to affect our lives in the future", it must not only have great promise if successful, it must be highly likely to succeed in the research, development, production, deployment and competition phase of a life cycle. Anything in preliminary or in the early stages should be disqualified.

Disagree? Just think of all the exciting ideas in the past 40 years for technologies that promised to displace silicon as king of the hill in electronics. There must have been 2 or 3 such exciting preliminary ideas every year.

If TR wanted to make this top 10 list truly significant and respected, it should make the selection process transparent, or open it up to peer voting on the web. Perhaps a wiki on "Top 10" might be the way to go.

2456 Days Ago

11/10/2008

More efficient to just burn it?

If one were to just burn the cellulose in a power plant, and use the electricity to recharge plug-in electric or hybrid vehicles, how would that compare to the fermentation->butanol->interal combustion engine route, in terms of vehicle miles per ton of biomass?

2265 Days Ago

05/20/2009

Food Science Can Help

Scientists trained in food science can help with this enzyme research; go to the site http://food-science-jobs.com/

1644 Days Ago

01/31/2011

Scope of Bioethanol Production in Pakistan

Pakistan is agricultural state and Nuclear Power. Most of population is living in rural areas and are related to agriculture by profession. They are hard workers and well traind farmers. Most of the agricultural area of country is cultivated with traditional crops like Wheat, Rice, Maize, Cotton and brassica. The Biomass of these all crops is Lignolossic, only 25 % is used as animal feed and domestic fuel and 75% is left /burnt in the fields. Some area is unfertile where Keller grasses and bushes are grown which all are useless for these farmers. Note that all types of plant biomass are rich source of cellulose which can be utilized for the production of bioethanol. Entire process of bioethanol production from lignocellulosic plant biomass consists of four steps (1) Pretreatment (2) Sccharification (3) Fermentation (4) Purification.

Pakistan is the ideal state for International Industrialists because cheep plant biomass and labour (manpower) are easily available. People can provide plant biomass to bioethanol industries and earn handful money to up lift their daily lives.

Being a Nuclear Power, Pakistan must develop Bioethanol technology by which industrialists and farmers may produce fuel grade bioethanol at their field level to overcome the shortage of fossil fuel. Recently Ministry of science and technology has funded many projects for the production of bioenergy from plant biomass in the country. Development of the process will strengthen the technologi-cal base of our country in addition to saving foreign exchange. This project will also produce technical man power which will be helpful for the development of biofuel industry in Pakistan which is the need of the day.